Thermal ink-jet printing has traditionally targeted office and home printing applications, as well as CAD plotting markets, where customers demand crisp, clean lines and text. Small, precise dots have traditionally been the goal for design engineers. However, in producing smaller dots and placing them on the media with higher resolution (600 dpi and beyond), such ink-jet designs are susceptible to imaging artifacts, such as banding, caused by droplet trajectory errors. Images produced with these ultra small dots are sensitive to horizontal and vertical axis directionality errors. For example, a dot that is roughly 1/600.sup.th inch in diameter can cause objectionable artifacts with even a 1/1200.sup.th inch trajectory error (roughly 50% error). Nonetheless, small dots are one of the better ways to image color. However, there are developments using thermal ink-jet (TIJ) technology in monochrome imaging applications, including black and white photography, monochrome graphic arts, and medical imaging. When producing monochrome images, ultra small droplets may not be the only path to acceptable images. Moreover, many of these monochrome imaging applications do not have the need for crisp text and sharp lines, further mitigating the dependence on small drops.
Halftoning small dots is one way to produce monochrome images (e.g., newspapers, laser printers, and the like), but the images lose much information, especially on the micro level. With TIJ technology, one can use multiple passes and multiple levels of gray placed on the media with a high precision and still preserve much information even on the micro level. Individual pixels could be of one several thousand different shades of gray. Unfortunately, using relatively small dots, TIJ is still susceptible to trajectory errors that lead to imaging artifacts. An organization designing and manufacturing TIJ monochrome printers could invest significant resources to control small dot trajectory errors and achieve acceptable image quality. In contrast, it would be desirable to develop a printing scheme that imaged with the existing trajectory errors without the deleterious effects of those trajectory errors.